AArch64 OpenEmbedded ARM Fast Models 14.04 Release

The AArch64 Open Embedded Engineering Build for ARM Fast Models for ARMv8 is produced, validated and released by Linaro, based on the latest AArch64 open source software from Tianocore EDK2 (UEFI), the Linux kernel, ARM Trusted Firmware and OpenEmbedded. It is produced to enable software development for AArch64 prior to hardware availability, and facilitates development of software that is independent of the specific CPU implementation. This build focuses on availability of new features in order to provide a basis for ongoing and dependent software development.

Linaro releases monthly binary images of this engineering build. This release includes Linaro OpenEmbedded images for Versatile Express, Base and Foundation Fixed Virtual Platform (FVP) models from ARM. Sources are also made available so you can build your own images.

About the AArch64 OpenEmbedded Engineering Build

This release has been tested on the Base FVPs from ARM (since September 2013), in addition to the updated Foundation FVP (since November 2013) and Versatile Express FVP.

The 'Base’ platform is an evolution from the Versatile Express (VE) platform that is better able to support new system IP, larger memory maps and multiple CPU clusters. The changes in the Base platform memory map require that software or device trees which specify peripheral addresses may need to be modified for the Base FVPs. Device trees for these FVPs are included in this release.

This build has been tested to work on the following FVPs:

Foundation_v8

FVP_VE_AEMv8A (previously called RTSM_VE_AEMv8A before v5.0)

FVP_Base_AEMv8A-AEMv8A

FVP_Base_Cortex-A57×4-A53×4

FVP_Base_Cortex-A57×1-A53×1

The Foundation_v8 FVP is free to use (download from ARMhttp://www.arm.com/fvp), while the others are licensed from ARM. More information on these specific FVPs is included with this release documentation.

The Base and Foundation FVPs use the following software for boot and runtime firmware services in this engineering build:

note: it is intentional that we suggest using the GICv2 DTB file, whilst specifying GICv3 on the model command line. In this mode, you are using the GICv3 controller in GICv2 compatibility mode, which is the default recommended by ARM.

Booting the image on the Foundation Model using the AXF file

If you are using an older version of Foundation Model (i.e. older than version 0.8.5206) and wish to use a pre-built image, you can simply unzip the downloaded pre-built image and the img-foundation.axf file and run the following command:

Building UEFI

ARM Fast Models

Built from ARM’s Fast Model toolkit, ARM provides a number of ready-to-use simulation models of platforms containing ARM processors, referred to as Fixed Virtual Platforms. This OpenEmbedded Engineering Build is designed to work with a number of those FVPs which contain ARMv8 processors:

Foundation_v8

FVP_VE_AEMv8A (previously called RTSM_VE_AEMv8A before v5.0)

FVP_Base_AEMv8A-AEMv8A

FVP_Base_Cortex-A57×4-A53×4

FVP_Base_Cortex-A57×1-A53×1

There are two primary platform definitions used by the FVPs:

VE – a replica of the ARM Versatile Express hardware development boards

Base – an evolution of Versatile Express that can support larger memory maps, multiple clusters and some new standard peripherals

The Foundation platform is a subset of the platform peripherals in the Base platform.

The following table describes the essential differences between these ARMv8 models:

The platform support in each of these models does evolve gradually over time, this information is correct with respect to build 0.8.5206 of the Foundation_v8 FVP, and builds 0.8.5108 and 0.8.5202 of the other FVPs.

1Platforms that do not support the ARM Trusted Firmware need to use a bootwrapper for the kernel image

2The number of CPU cores in each cluster can be configured when running the AEMv8 FVPs

4The default Device Trees (fvp-base-gicv2-psci.dtb and fvp-foundation-gicv2-psci.dtb) only present a GICv2 interrupt controller node to Linux. However, there are alternative Device Trees (fvp-base-gicv3-psci.dtb and fvp-foundation-gicv3-psci.dtb) provided in this Engineering Build that includes the GICv3 node, which is needed for development of OS and hypervisor GICv3 support. It is also possible to configure the GIC to be GICv2 when running these FVPs.

The Foundation_v8 FVP is free to use and can be downloaded from ARM, the other FVPs are licensed from ARM. More information on the ARM FVPs and download links can be found on the ARM website http://www.arm.com/fvp.

OpenJDK FCS Release for AArch64

The 14.04 release of OpenJDK is a fully functional, stable release of OpenJDK. It has been extensively tested using test suites including the JTREG, JCK and Mauve test suites as well as real work applications such as Hadoop, Eclipse and industry standard benchmarks such as SPECjvm2008 and PECjbb2013. There are no known critical failures when used with standard options. There are a number of failures when used with certain non standard options. These failure are detailed below.

The release is being made available in two variants:

OpenJDK 8

The OpenJDK 8 release is based on the jdk8-b132 tag of the main OpenJDK 8 tree. This corresponds to the “General Availability” release announced on 2014/03/18.

OpenJDK 7

As JDK8 is a complete revision of JDK, a backport to OpenJDK 7 is provided for compatibility with the known and proven JDK7. This release is based on the jdk7u60-b04 tag of the JDK7 updates tree.

Supported HotSpot Technologies

Both OpenJDK releases support the Client (C1) and Server (C2) JIT compilers in addition to supporting the Template assembler based interpreter and the 'Zero’ C based interpreter.

The default execution model is Server (C2) JIT using Tiered Compilation. Under this model code is first executed by the Template nterpreter. When code is deemed to be 'hot’ it is compiled initially using the Client (C1) JIT. The code compiled by the C1 JIT contains profiling code. If a method is deemed to be sufficiently hot it is recompiled with the Server (C2) JIT. The C2 JIT uses the profiling information collected by the C1 JIT to generate highly optimal execution path targetted code.

Different execution models may be selected using the following command line options.

-server – The default Server (C2) JIT

-client – The Client (C1) JIT

-Xint – The Template assembler based interpreter

-zero – The 'Zero’ C based interpreter

In addition the following options may be specified

-XX:+TieredCompilation

The default with -server. Enable Tiered compilation as described above.

-XX:-TieredCompilation

Disable Tiered compilation. Code is compiled directly with the Server (C2) JIT. Using this option will generate less efficient code because the profiling information gathered by the C1 compiler will not be available.

Note: that for the hosted tests, if the daily test determines that there has been no change to the source tree then the tests are not run. This is done to reduce bandwidth on the email list.

Note: In spite of the slowness of the tests executed on the foundation model, which prevents complete test execution on a daily basis, we periodically verify that the complete test execution provides the very same identical results on both the foundation model and the real h/w in our lab. Please note that no performance numbers are posted to the mailing lists, only functional pass/fail test results.

Known Failures

-XX:+UseBiasedLocking causes a fatal error

The implementation of Biased Locking has not been completed in the AArch64 port and use of this option may cause fatal errors.

Workaround: Do not use the -XX:+UseBiasedLocking option.

Assertion failure with -XX:-InlineObjectHash and -XX:-ProfileInterpreter

This combination of options may cause the following fatal error to be generated:

assert(false) failed: this call site should not be polymorphic

Workaround: Do not use this combination of options.

Acknowledgements

We would like to thank RedHat, and especially Andrew Haley and Andrew Dinn, for starting this project and for the huge efforts they have put in to deliver a high quality, high performance Java solution for AArch64 which is available as Open Software. We would also like to thank all in the Open Source community who have contributed to the projects, either through bug fixes or suggestions or through testing early releases of the software and submitting bug reports.